This invention is an improvement to structures such as disclosed in U.S. Pat. Nos. 3,598,238 to Collins, No. 4,533,471 to Collins and U.S. application to Collins, Ser. No. 602,818, filed Apr. 23, 1984, now U.S. Pat No. 4,608,159. The structures shown and described in these patents and application are hereby incorporated by reference.
This invention satisfies a need for automatic self-cleaning filter apparatus which will cyclically clean the filter element of one of two filter units while filtering a filtrate sample through the alternate of the two filter units with the filter apparatus being of relative large capacity and capable of operating for an extended period without need to stop the filtering apparatus for changes in filter elements.
All of the known prior art is cited in the above referenced patents and patent application.